1. Field of the Invention
This invention relates to a paper feeding device used in an image forming mechanism of a laser printer, a copier or the like.
2. Description of the Related Art
FIG. 5 is a perspective view of a prior paper feeding device, FIGS. 6A to 6C are schematic diagrams for explaining its paper feeding operation, and FIG. 7 is its control flowchart.
As shown in FIG. 5, the prior paper feeding device comprises paper feed rollers 2 and 3, paper hand feed rollers 4 and 5 disposed in a paper hand feed path 1, and a drive section 6 for driving the paper feed rollers 2 to 5, the drive section including a motor 7, a gear mechanism 8, and a clutch 9. A paper feed detect switch 10 is provided for the paper feed rollers 2 and 3. A hand feed detect switch 11 is provided close to the paper hand feed rollers 4 and 5.
In the above arrangement, while the paper feeding device is in wait state, when paper 12 is sent to the hand feed path 1, the hand feed detect switch 11 is turned on as shown in FIG. 6A. When this occurs, the motor 7 is turned on and the paper 12 is fed by the hand feed rollers 4 and 5 (FIG. 6B). When the paper 12 comes to the paper feed detect switch 10, the clutch 9 is disengaged to prevent the paper 12 from being sent beyond the paper feed rollers 2 and 3. At this time, the leading edge of the paper 12 is located at the paper feed rollers 2 and 3 held by the clutch 9. Then, the motor 7 is turned off, the clutch is engaged, and the paper feeding device waits for a request to print (See FIG. 6C). After this, when a request to print is given, the motor 7 is turned on to drive the paper feed rollers 2 and 3 to send the paper to a printing section. When the paper is extracted, the hand feed detect switch 11 is turned off, and the process returns to the initial wait state. In FIG. 7, the process "FEED PAPER TO CASSETTE" indicates a case in which an automatic paper feed mechanism is operated.
However, in the above-mentioned prior art, the paper hand feed mechanism necessitates the switch 11 for detecting a hand feed, paper hand feed rollers 4 and 5, and a special holding mechanism. For this reason, the number of parts used is large, and their control is complicated.
It is therefore an object of the present invention to provide a paper feeding device having the reduced number of parts required.
As shown in FIGS. 1 and 2, the paper feeding device according to the present invention comprises paper feed rollers 24 and 25 disposed in the paper hand feed path 23, a drive section 26 for driving the paper feed rollers 24 and 25, a paper feed detect switch 27 arranged in front of and close to the paper feed rollers 24 and 25, and a controller 29 for outputting control signals to the above-mentioned drive section 26 to drive the paper feed rollers 24 and 25 in response to ON action of the paper feed detect switch 27 to pinch and hold the leading edge of the hand-fed paper 28 between them.
In the above-mentioned paper feeding device, in the case of paper hand feed, while it is in a wait state, when the paper 28 is supplied through the paper hand feed path 23 as shown in FIG. 3A, the paper feed detect switch 27 is turned on. Then, the controller 29 sends a signal to the drive section 26, whereby the paper feed rollers 24 and 25 are halted. Therefore, the paper 28 is not fed. While this state is maintained for a fixed period of time, the leading edge of the paper 28 is aligned at the paper feed rollers 24 and 25 (See FIG. 3B). After this, the paper feed rollers 24 and 25 are driven to feed the paper 28 by a fixed amount, whereby the paper 28 is pinched and held between the paper feed rollers 24 and 25 (See FIG. 3C). Then, the drive section 26 is turned off and waits for a request to print.
When a request to print is given, the controller 29 causes the paper feed rollers 24 and 25 to rotate, thereby supplying the paper 28 to the photosensitive body 35. At this time, when the paper 28 is extracted, the paper feed detect switch 27 is turned off, the paper feeding device returns to the initial wait condition.
According to the present invention, in the case of paper hand feed, the leading edge of the hand-fed paper is pinched and held by the paper feed rollers, and therefore, the paper can be held without a provision of a switch for detecting hand feed and an additional paper holding mechanism, so that the number of parts required can be reduced, and the reliability of paper feeding operation can be improved.
Further, there is no need to connect an additional paper holding mechanism to the motor of the drive section, therefore, it is possible to reduce the motor load.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiment of the invention as illustrated in the accompanying drawings.